Justice Wiley seems right to me when he says that, under the statute, continuous sexual abuse of a child doesn't necessarily require an intent to sexually arose one's self, and that whatever the alleged flaws of the jury instruction given here, they don't really matter in this particular case, since the only alleged basis for defendant's digital penetration of this child was to "punish" her. That's not a good enough reason. You can ground the child or do other stuff (like taking away their phone -- always effective) to punish them, but molesting them is not one of the permissible options. Rightly so.
I'm less confident that Justice Wiley is correct when he says "This mental state—requiring only proof that Canales voluntarily inserted his finger or penis into his stepdaughter’s vagina, without any further level of mental culpability—satisfies the presumption of mandatory culpability. Canales does not suggest, nor can we imagine, any morally innocent reason for him to decide to penetrate her."
Justice Wiley himself suggests, later on in the opinionlater on in the opinion, that there might well be acts that constitute literal violation of the statute and yet wouldn't (and shouldn't) constitute a crime. Inserting a rectal thermometer into a child's anus, for example. What Canales did was admittedly different. But I could at least "imagine" a situation in which digitally penetrating a child would be morally innocent (though, admittedly, not many). For example, a parent who was a gynecologist might perhaps morally innocently place his (or her) finger in a child for medical reasons; e.g., during a legitimate pelvic exam. Perfectly permissible, in my view.
So I think there is, in fact, a mens rea requirement here. Maybe not the requirement that one engage in the act for sexual arousal. But the jury instruction is, in fact, wrong when it says (and when the Court of Appeal says) that there is "no heightened mental requirement beyond his voluntary decision to perform the physical movements of the act." Otherwise the gynecologist is also guilty, for they surely perform the physical movements of the act, and voluntarily so.
The erroneous instruction here may well be harmless, because there was no evidence that Mr. Canales here performed the act for a morally legitimate reason. But it's still wrong, and should be revised. The statute does, in fact, require more, in my view. (At least unless we want to start throwing tons of doctors in prison.)
One last thing. Mr. Canales denied everything at trial, but the jury took only an hour to convict him, and he was sentenced to 60 years to life in prison. The one strike law doesn't, in fact, apply to him, so the Court of Appeal remands for resentencing. Nonetheless, he's going to almost certainly spend all (or nearly all) of his life in prison, and the jury didn't have much trouble at all in convicting him. That's a fairly good example of the prosecution winning big -- and easily.